Joint for metal-sheathed cables.



No873,2l5. PATENTBD DEC. l0, 1907. C. W. DAVIS. JOINT POR METAL SHEATHED CABLES.

APPLXOATION FILED MAR. 311906.

6 Il I e v 75 2 ga/La 0, mvENfroR lUNITED sTATns PATENT oFFron.

CHARLES W. DAVIS, OF EDGEWORTH, PENNSYLVANIA, ASSIGNOR TO STANDARD vUNDER,- GROUND CABLE COMPANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OF PENN- SYLVAN IA.

JOINT FOR METAL-SHEATHED CABLES. i

Patented nec. 1o, 1907'.

.Application filed March Sli-1906. Serial No. 309.199.

T o all whom it may concern:

Be it known that I, CHARLES W. DAVIS, residing at Edgeworth, in the county of Allegheny and State of Pennsylvania, a citizen of the United States, have invented or discovered certain new and useful Improvements in Joints for Metal-Sheathed Cables, of which improvements the following is a specification.

In the accomp an ing drawings which form.' part of this speci cation the figures show` ypartly in-elevation and partly in longitudinalsection my improved cable-joint in three al# ternative forms. f

Corresponding parts in lthe several figures bear the same reference numerals in each case.

A joint for a metal-sheathed cable which shall insulate adjacent sections ofthe sheath is most desirable for, in service, these metallic sheaths are otherwise apt to pick` up stray or lost currents, and, through faults in the cable insulation itself, to become of like potential with the included conductor; and such accidental currents flowing in the sheath tend to disintegrate and destroy the sheath both through electrolytic action 4andM-in case the currents are at all heavythrough fusion.v j

In the drawings, adjacent ends of a cable, 1, are shown united by my improved joint, The cable ordinarily consists of a core, 2, whichmay be a single integral conductor or a plurality of independent strands coperating to carrya single current, and thusl forming a single compound conductor, Ior

' again, these strands', insulated from one another," may carry distinct and independent currents. Thls core 2 1s contained 1n an 1n sulating envelop, 3 5 and the whole is inclosed the cable sheath on opposite sides of the point of union ofthe core by they ordinary wiped joint, which has been found -to be in service the most efficient connection, and these metal thimbles, separated from one an other so as to break the continuity of the conductive sheath, are in turn united by the annulus of insulating material. And this insulating material is not a yielding elastic material so unserviceable but so essential in the older forms of insulating joint, but a strong unyielding and permanently eihcient material, such as electrose, Imicanite or porcelain.

The parts of my improved joint are preferably assembled in the following manner. The case or shell, comprising the metallic thimbles and the non metallic insulating annulus, will -ordinarily be completed in the shop. The material of which the annulus is formed must be sufliciently tenacious 5 it is preferably worked in plastic state, and capable of being shaped or pressed into form; it must be such as to make sufliciently intimate contact with the bodies of the thimbles, that there may be no ingress of moisture it should have a coefficient of expansion approximately the same as that of the metal of which the thimbles are formed; and it should be (when the shell or case is of the particular form shown in Fig. 1 or Fig. 3) of such quality as to be unaffected by the heat conveyed through the thimbles when the wiped solder Yjoints presently to be described are being formed. I preferably employ a compound resembling the material known to thetrade as .electiose, but modified to withstand high temperature Without becoming plastic. Such a .1nateria1, brought to a plasticcondition, is

moldedto shape upon the pair of thimbles first brought into proper position, indicated in the drawings. That portion of the surface of the thimbles upon which the annulus is formed may be shaped to afford a more securejunion; and this is indicated in the corrugations, 11, upon thimbles 7. It will be observed from the drawings that this shell, whilel having great mechanical strength by virtue of the short space between adjacent ends of the pair of thimbles which form part of it, has a large leakage surface on its exposed outer surface. By leakage surface is meant the surface of insulating material separating or intervening between adjacent conductor surfaces, and over which any leakage must pass. The construction is in this respect of great practical value. Returning then to the assembling of the parts, the adj acent ends of the cable to be united are first prepared by stripping away the sheath and insu. ation and laying bare the core, and a case or shell composed as described is threaded upon one of the cable ends. The exposed conductor ends are then brought together and united in any preferred manner. In the drawings a sleeve, 5, which will be of metal, is shown surrounding' the adjacent ends of the single integral conductor which in this case constitutes the core of the cable. This sleeve 5 is sweated to place with solder. The connections and the exposed portion of the conductors are then insulated if desired, with insulating tape or otherwise. case 1s then advanced until it surrounds and incloses the connection formed in the core of or shell are then secured to the sheath 4 by the familiar wiped solder joints, indicated at 8.

l/Vhile I preferably employ a material for the annulus which will not be injuriously affected by the heat conveyed to it in the forming of the wiped joints, 8, I have in Fig. 2 shown ineans whereby the wiped oints may be formed without subjecting the annulus to a high temperature. Each thimble, 7a, is made in two sections, the inner receiving the annulus 6 and the outer the wiped joint. These two sections may be separated by an interposed ring of insulation, 9, which may be a rubber gasket or other preferred substance, and the sections may be made capable of secure union, as by a clamping ring, 10,

which when'the sections are assembled and' secured may be screwed to place.

lVhile 'I prefer to employ an annulus such as I have described, which is molded to place,

The shell or that the space within the shell or case may after the parts are assembled as described be e left vacant or lled'in any manner known to the art with insulating material.

I claim herein as my invention:

1. An insulated joint for a metal-sheathed cable which includes a case or shell formed of a pair of thimbles connected to the sheath on opposite sides of the point of union of the cable core and extending into proximity to one another, and an annulus of insulating material surrounding such point of union, the inner surface thereof coverin the 'proximate ends of said thimbles and t e outer surface thereof exposed `for a distance greater than that which separates the thirnbles, substantially as described.

-2.y An insulated joint for a metal-sheathed cable which includes a case or shellformed of a pair of thimbles connected to the sheath on opposite sides of the point of union of the cable core and extending into proximity to one another, the outer surfaces of said thimbles being corrugated, and an annulus of insulating material surrounding such point of union, and connecting said thimbles, covering the proximate ends of said thilnbles over the corrugated surfaces thereof, and exposed outwardly over a distance Greater than that which se arates said thiinlbles, substantially as descri ed.

3. An insulated joint for a metal-sheathed cable which includes a case or shell formed of a pair of thimbles connected to the sheath on opposite sides of the point of union of the cable core and extending into proximity to one another, and an annulus of insulating material formed upon and uniting the proximate ends of said thimbles and surrounding such point of union, and outwardly exposed over a distance greater than that which separates the thimbles, substantially as described.

4, A thimbleI for use in forming an insulated joint for metal-sheathed cables, such thimble being of suitable size to surround the cable adjacent to the point of union, and composed of two substantially annular portions of substantially equal diameter, a third ring of heat-insulating substance interposed between the abutting ends of the two first-` CHARLES W'. DAVIS.

l/Vitnesses:

CHARLES BARNETT, BAYARD H. CHRISTY. 

